FIG. 1 depicts a conventional method 10 for forming a read transducer. The conventional method 10 commences after structures in the conventional read transducer have been formed. For example, shield(s), write transducer(s) or other structures may have been fabricated. A conventional magnetoresistive sensor that is defined in the track width direction and conventional hard bias structures are provided, via step 12. Step 12 includes formation of the conventional magnetoresistive stack. A conventional antiferromagnetic (AFM) layer, a conventional pinned layer, a conventional nonmagnetic spacer layer, and a conventional free layer may have been deposited. In addition, the layers may have been masked and ion milled in the track width direction to define the sensor in this direction using step 12. The track width direction is parallel to the air-bearing surface (ABS) and generally perpendicular to the layers of the magnetoresistive stack. Further, a thin insulating layer on the sides of the conventional magnetoresistive sensor in the track with direction may be provided. Further, conventional hard bias materials are deposited in step 12.
A mask that covers the conventional hard bias structure and the conventional magnetoresistive sensor is provided, via step 14. The mask is used to define a stripe height of the conventional magnetoresistive sensor. The stripe height direction is generally perpendicular to the ABS. In the region near the magnetoresistive sensor, the mask terminates substantially the same distance from the ABS across the magnetoresistive sensor and the hard bias material(s).
The magnetoresistive sensor and hard bias structure are milled with the mask in place, via step 16. Fabrication of the magnetic transducer may then be completed. For example, other structures such as shield(s) and/or write transducers may be provided. In addition, lapping or other processing may change the final stripe height of the magnetoresistive sensor.
FIG. 2 depicts a perspective view of a conventional magnetic read transducer 20 used in reading a media (not shown) and fabricated using the method 10. For clarity, only a portion of the conventional read transducer 20 is shown. Referring to FIGS. 1-2 the conventional read transducer 20 is shown after completion of step 16 of the conventional method 10. The conventional magnetic transducer 20 is formed on substrate 22 and includes conventional magnetoresistive sensor 24 and conventional hard bias structure 26A and 26B. The track width, TW, is defined in step 12. The stripe height, SH, is determined in step 16 and by the mask provided in step 14. The stripe height determined indicates not only the position at which the conventional magnetoresistive sensor 24 terminates, but also the location at which the hard bias structures 26A and 26B substantially terminate.
Although the conventional read transducer 20 formed using the method 10 functions, the trend in hard disk drives is toward higher densities. At higher densities, such as greater than or equal to four hundred gigabits per square inch, the track width TW is small. At such densities, the signal-to-noise ratio is desired to be enhanced. An improvement in the signal-to-noise ratio may be achieved by improved biasing of the conventional magnetoresistive sensor 24. Consequently, a mechanism for improving the conventional hard bias structures 26A and 26B is desired.
FIG. 3 depicts another conventional method 30 for fabricating a conventional read transducer. The conventional method 30 commences after structures in the conventional read transducer have been formed. For example, shield(s), write transducer(s) or other structures may have been fabricated. The magnetoresistive stack is provided, via step 32. Step 32 typically includes blanket depositing an AFM layer, a pinned layer, a nonmagnetic spacer layer, and a free layer, as described above. The magnetoresistive stack is masked and milled to define the stripe height, via step 34. After the milling in step 34, alumina is typically used to refill the region from which the magnetoresistive sensor stack was removed. The magnetoresistive sensor is defined in the track width direction, via step 36. Thus, the stripe height and track width of the conventional magnetoresistive sensor are defined in steps 34 and 36. The conventional hard bias structure(s) are also provided, via step 38.
Although the conventional method 30 can be used to fabricate a conventional read transducer, there are drawbacks. However, in the step 36 of defining the magnetoresistive sensor in the track width direction, the alumina refill mills at a different rate than the magnetoresistive sensor. Consequently, the topology on which the hard bias structure is deposited is not flat. This topology is transferred to the conventional hard bias structure, which gives rise to magnetic instabilities in the conventional hard bias structure. Therefore the conventional hard bias structure's ability to adequately bias the conventional magnetoresistive sensor may still be compromised. Thus, the signal-to-noise ratio of the conventional read transducer may be adversely affected.
Accordingly, what is needed is a system and method for improving the signal-to-noise ratio of the magnetic transducer.